Obstruction removal system

ABSTRACT

An obstruction removal device is described, having one or more engaging members which can engage portions of the clot. The one or more engaging members have a collapsed, delivery state, and an expanded, deployed state.

RELATED APPLICATIONS

This application claims priority to U.S. Provisional Application Ser.No. 62/426,113 filed Nov. 23, 2016 entitled Obstruction Removal System,which is hereby incorporated herein by reference in its entirety.

BACKGROUND OF THE INVENTION

The present invention relates to devices used to capture and removeobstructions, such as clots or other matter, from the vascular system,and delivery of these devices to a target area within the vascularsystem.

The buildup of thrombi in vasculature can lead to formation of bloodclots. The formation of clots can result in restricted blood supply todownstream areas of the vasculature. When located in the neurovascularsystem, these clots can lead to stroke.

Recent technologies to remove clots utilize devices designed to hold andcapture the clot, followed by withdrawal of the device to physicallyremove the captured clots from the body. Several of these devices mayfail to capture the clot in its entirety, or may promote clotfragmentation which may allow thrombi to dislodge and accumulate atanother site, thus continuing the risk of stroke. In addition, severalof these devices may promote endothelial denudation due to high frictionbetween the device and the vessel wall.

There is need for an obstruction removal device which reduces thelikelihood of fragmented thrombi staying in the vasculature whilemaximizing the chance of mechanically capturing the clot, and limitingthe risk of endothelial denudation.

SUMMARY OF THE INVENTION

In one embodiment according to the present invention, an obstructionremoval device is described having a proximal axial core structure, adistal bumper structure and one or more engaging members mounted to thedistal bumper structure.

In another embodiment according to the present invention, an obstructionremoval device is described having a proximal structure, distalstructure, and one or more connected engaging members between the twostructures.

In another embodiment according to the present invention, an obstructionremoval device is described having a proximal structure, distalstructure, and one or more connected engaging members between the twostructures, where at least one of the engaging members acts as a filter.

In one example of the previously described embodiments, the pluralengaging members are substantially similar to each other.

In another example of the previously described embodiments, some of theplural engaging members are not substantially similar to the otherengaging members.

In another example of the previously described embodiments, some of theplural engaging members actively engage the clot while one or more ofthe remaining engaging members do not engage the clot.

In one embodiment, the obstruction removal device is sheathed within adelivery device and delivered through a catheter.

In another embodiment, the obstruction removal device is delivereddirectly through the catheter.

In another embodiment, the device is used to retrieve foreign objects.

In one embodiment, the obstruction removal device comprises a pluralityof obstruction engaging members linked together with individuallinkages. The linkages link a pair of engaging members together.

In one embodiment, the obstruction removal device comprises one or moreengaging members where the engaging members include some struts spanningthe entire length of the elements and some struts that do not span theentire length of the elements. Some of these struts have radiopaquemarkers to augment imaging of the obstruction removal device.

In one embodiment, the obstruction removal device comprises one or moreengaging members where the engaging members include twisted struts. Thetwisted struts provide a non-parallel surface which contacts the bloodvessel wall, better enabling the twisted struts to scrape the vesselwalls and remove hard or calcified clot.

In one embodiment, the obstruction removal device comprises one or morecatch elements and one or more engaging members which engage the clot.In one embodiment, the catch elements and engaging members sit on acommon core wire. In one embodiment, the catch elements can slide on orover the core wire while the engaging members are fixed to the corewire.

In one embodiment, the obstruction removal device comprises a pluralityof fixed non-rotating engaging members which are rotatably offset fromeach other a certain number of degrees.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other aspects, features and advantages of which embodiments ofthe invention are capable of will be apparent and elucidated from thefollowing description of embodiments of the present invention, referencebeing made to the accompanying drawings, in which

FIG. 1 is an engaging member used in an obstruction removal device.

FIG. 2 is another view of the engaging member used in an obstructionremoval device.

FIG. 3 is an obstruction removal device according to one embodiment ofthe present invention;

FIG. 4 is an obstruction removal device according to another embodimentof the present invention;

FIG. 5 is an exploded view of the obstruction removal device shown inFIG. 4;

FIG. 6 is a magnified view of the proximal engaging member of theobstruction removal device of FIGS. 4 and 5.

FIG. 7 is an obstruction removal device according to another embodimentof the present invention;

FIG. 8 is an exploded view of the obstruction removal device shown inFIG. 7;

FIG. 9 is one of the distal engaging members used in the device shown inFIGS. 7 and 8.

FIGS. 10-12 illustrate a method of deploying the obstruction removaldevice described in the previous embodiments.

FIG. 13 illustrates a hypotube used to create an engaging member

FIGS. 14-16 illustrate a process used to help set the final shape of anengaging member

FIG. 17 illustrates an obstruction removal device comprising engagingmembers where the engaging members include some struts than span thelength of the engaging member and some struts that do not span thelength of the engaging member.

FIGS. 18a, 18b, 18c, and 18d illustrate various views of the obstructionremoval device of FIG. 17.

FIG. 19 illustrates a marker coil used on the engaging member struts ofFIGS. 17-18 d.

FIG. 20 illustrates an engaging member used in an obstruction removaldevice where the engaging member has a twisted strut pattern.

FIG. 21 illustrates a hypotube used to create the twisted strut patternengaging member of FIG. 20.

FIGS. 22-24 illustrate an obstruction removal device comprising a catchelement and an engaging member.

FIG. 25 illustrates an obstruction removal device comprising multiplecatch elements and multiple engaging members.

FIG. 26 illustrates a linkage system used between engaging members of anobstruction removal system, where the engaging members are capable ofindependent rotation.

FIG. 27 illustrates an obstruction removal device with fixed engagingmembers.

FIG. 28a illustrates a first embodiment of an obstruction removaldevice's interaction with thrombus against a vessel wall.

FIG. 28b illustrates a second embodiment of an obstruction removaldevice's interaction with thrombus against a vessel wall.

FIG. 29 illustrates an engaging member composed of drawn filled tubewires.

FIG. 30 illustrates an engaging member in which half of its structure iscomposed of drawn filled tube wires and its other half is composed oflaser cut struts.

FIG. 31 illustrates an engaging member in which half of its structure iscomposed of drawn filled tube wires and its other half is composed ofbraided wires forming a mesh concave filter.

FIGS. 32 and 33 illustrate an engaging member that has a radially offsetshape with a flat/straight side and a curved side.

FIG. 34 illustrates a clot retrieval device having two flowering petalengaging members that open in a distal direction.

DESCRIPTION OF EMBODIMENTS

Specific embodiments of the invention will now be described withreference to the accompanying drawings. This invention may, however, beembodied in many different forms and should not be construed as limitedto the embodiments set forth herein; rather, these embodiments areprovided so that this disclosure will be thorough and complete, and willfully convey the scope of the invention to those skilled in the art. Theterminology used in the detailed description of the embodimentsillustrated in the accompanying drawings is not intended to be limitingof the invention. In the drawings, like numbers refer to like elements.

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in, the art to which this invention belongs. It willbe further understood that terms, such as those defined in commonly useddictionaries, should be interpreted as having a meaning that isconsistent with their meaning in the context of the relevant art andwill not be interpreted in an idealized or overly formal sense unlessexpressly so defined herein.

For the purposes of the terminology described below, the terms clot,thrombus, embolus, and obstruction can be used synonymously. Though anobstruction removal device is described, the device can also be used tocapture clots, thrombi, emboli, foreign bodies, or other matter.Engaging members on the device can engage clot, thrombus, embolus,foreign bodies, obstructions, or other matter.

FIGS. 1 and 2 show an engaging member 100 used with the obstructionremoval device of the present invention. One or more engaging membersare used as part of an obstruction removal device in order to engagethrombus which can accumulate within a vascular system. General engagingmember shapes can include, but are not limited to, round, oval,elliptical, hourglass, spherical, basket, stent, countered, rectangular,prismatic, cage. Each engaging member 100 has a number of struts 101which define a number of cells, or openings 102, and a pair of opposingholes 103 and 104. For the sake of convention, hole 103 is a distal holeand hole 104 is a proximal hole.

Each engaging member may be uniquely configured with different struts,cells, cell sizes, materials, and/or shapes. The strut design can have alinear, wave, sinusoidal, or zig-zag pattern, or can have anon-symmetrical design (i.e. where struts on one side of the engagingmember are not mirrored on the other side of said engaging member). Thenon-symmetrical strut design may help facilitate a rotational componenton the member as it travels through a vessel, by shifting the center ofgravity from the geometric center of the engaging member. This ease ofrotation makes it easier for the engaging members, and therefore theobstruction removal device, to move more easily through the anatomy,especially after the clot has been engaged and the device is beingpulled back through the vasculature. This ease of rotation can alsolimit the amount of damage to the vessel wall due to excessive contactfriction by limiting the damage to a particular section of the wall. Theengaging members may have either identical or unique designs on each endof the engaging member. This may be done by varying shape of the strutsand/or cells, and/or varying the cell density of each end, thus—forexample—allowing for large cell sizes on one end and smaller cell sizeson the opposing end. This variability may allow for different propertiesto allow for enhanced ability to engage the clot, or enhanced ability totrack the obstruction removal device and deployed engaging membersthrough the vessel.

FIG. 2 shows an engaging member 100 having a plurality of struts 101having different thicknesses. More specifically, a plurality of endstruts 101 a branch out from the material defining proximal hole 104,and one or more of these struts 101 a split to form struts 101 b. Struts101 b are shown with features 105 protruding therefrom. Features 105 maybe any interruption in the otherwise continuous surface of the strut101. Non-limiting examples include barbs, bumps, protrusions, spikes,branches, nubs, and the like. The struts 101 b are then shown as joiningan adjacent struts 101 b to form thicker struts 101 c, which then splitagain to form additional struts 101 d, also shown as having features105. These struts 101 d then join together again to form thicker struts101 e, which are connected to define distal hole 103. As such, it isseen that, in this particular embodiment, the struts interconnect toform a web of struts that span from the proximal hole 104 to the distalhole 103.

Another strut configuration could utilize a single strut pattern. Anexample includes a contiguous, helical strut configuration runningbetween the proximal and distal ends of the engaging member, or runningbetween a portion of the length spanning the proximal and distal ends ofthe engaging member.

Each engaging member has a collapsed configuration when sheathed withina delivery device, and takes on an expanded configuration as shown inFIGS. 1 and 2 when unsheathed. Each engaging member can beself-collapsible and self-expandable based on whether an external forceis applied to constrain it (as would be the case when sheathed in adelivery device), or no constraining force is present (as would be thecase when unsheathed).

The engaging member may be formed from nitinol, or a similar material,and may be laser cut to achieve the profile shape. Other materials andother cutting and/or machining processes would fit within the scope ofthe invention.

The distal and proximal holes, 103 and 104, on respective distal andproximal end of the engaging member, may facilitate placement of acommon rod on which each engaging member sits, or they may fit separateconnection pieces to connect multiple components of the obstructionremoval device with the respective engaging members.

FIG. 3 illustrates an obstruction removal device 200 according to oneembodiment of the present invention. The obstruction removal devicecomprises a proximal core structure 201 at one end of the device, adistal bumper structure 202 connected to the proximal core structure201, and one or more engaging members 203 mounted to the distal bumperstructure 202. In one example, the device is pushed and/or pulled fromthe core structure 201 end. A pusher may sit under the core structure,or the core structure itself may act as a pusher.

Core structure 201 may be made of a variety of materials, including, butnot limited to, nitinol, stainless steel, cobalt chromium, or apolymeric material such as PTFE, Pebax, TPE, Engage, polyethylene, orother similar materials. Core structure configurations can include, butare not limited to, a coil, a braid, or a coil/braid combination.

The bumper structure 202 may be made of a radiopaque material,including, but not limited to, platinum, tantalum, palladium, or othersimilar material. A radiopaque material is preferred to make imaging ofthe device easier during the device insertion procedure, althoughnon-radiopaque materials may also be used. The engaging members beingmounted to the bumper structure, where the bumper structure is made of aradiopaque material, aids in imaging the device during the clot removalprocedure. The engaging members may be mounted to the bumper structurein several ways. For example, the bumper structure may have a threadedouter profile, where the holes of the engaging members have acorresponding receiving structure to rotatably mate to the threadedbumper structure profile. Alternatively, the bumper structure may have anon-threaded outer configuration, and the engaging members may beaffixed to the bumper structure by a heat treatment procedure, such aswelding. Other mechanical means or other heat treatment procedures canalso be used to affix the engaging members to bumper structure.

FIG. 4 illustrates an obstruction removal device 300 according toanother embodiment of the present invention. The obstruction removaldevice 300 includes a proximal structure 301 connected to one or moreengaging members 303. There may be a distal structure 302 attached to adistal-most engaging member (labeled as 306 for clarity, though it maybe structurally the same or different as the other engaging members303). The one or more engaging members 303 are connected to the proximalstructure in such a way as to allow the one or more engaging members 303to rotate independently of the proximal structure 301. The one or moreengaging members 303 may be linked together to allow the engagingmembers 303 to rotate independently of each other as well, as discussedin more detail below. The obstruction removal device 300 is preferablypushed/pulled from one end of the proximal structure 301, thus the termsproximal portion structure and distal structure are used relative to thepushing/pulling end. Although five engaging members are illustrated inthe figure, fewer or more engaging members can be used. Like all of theembodiments described herein, the engaging members 303 are constructedwith one or more struts 101, as described above.

FIG. 5 illustrates an exploded view of an embodiment of the obstructionremoval device 300 of FIG. 4. The proximal structure 301 may include acore wire 307 which sits under a coil 309, which may sit under a tube310. The core wire 307 includes a flared end 308. The core wire 307 maybe made of nitinol, or a similar material, although other materials arewithin the scope of the invention. The coil 309 may be made of tantalum,or other radiopaque materials, although non-radiopaque materials mayalso be used. The tube 310 may be made of PET, or other polymericmaterial, although non-polymeric materials may be used as well. Theproximal structure also includes another coil 311 which is preferablymore gapped than coil 309, and can be made of a similar material. Coil311 sits between core wire 307 and the over-coil 309, and helps centercore wire 307 within coil 309. Proximal structure 301 is connected to aproximal engaging member 302, which can in turn be connected to anotherengaging member if more than one engaging member is used in theobstruction removal device.

The distal structure 302 includes a monofilament 315 which sits under acoil 316. Alternatively, multiple monofilaments can be bonded togetherto produce a monofilament structure 315. The monofilament 315 can bemade of a stretch-resistant polymer such as Engage, although othermaterials may be used. The coil 316 may be made of tantalum, or otherradiopaque materials, although non-radiopaque materials may also beused. Adhesive, preferably UV curable adhesive, 317 is used at both endsof the coil structure 316 in order to keep the monofilament 315 integralwithin the coil 316. In one example, the distal structure can act as aguidewire.

A distal structure 302 may be connected to the distal-most engagingmember 306. This distal structure may be radiopaque in order to aid inimaging of the device during deployment. In the embodiment of FIG. 5,the coil of the distal structure 302 fits within the hole 103 of thedistal-most engaging member 306, and a retaining piece 312 fits on theother end to keep the distal portion 302 integral with engaging member306. The retaining piece is welded within the interior of the structureof hole 103. The engaging member 306 can still rotate. The retainingpiece may be of a tubular construction, and may be made from nitinol,although similar materials can also be used. In order to aid in imaging,the retaining piece may be made from nitinol filled with a radiopaquematerial. Alternatively, the retaining piece may be coated with aradiopaque material to aid in imaging of the device during theprocedure. Alternatively, the retaining piece may be made of aradiopaque material.

The connection mechanism used to connect the engaging members togetheris shown in FIGS. 5 and 6. FIG. 6 illustrates the connection structureof engaging member 303, which is connected to the proximal structure 301of the obstruction removal device.

The connection mechanism includes a link 313 with two flared ends 314,and retaining pieces 312. The link 313 may be made of stainless steel,although similar materials may be used. The flared ends extend withinthe opposing holes 103, 104 of the engaging members being connected, andthe retaining piece 312 fits next to the flared end 314 to secure thelink 313 within the hole of the engaging member. This connectingstructure is used to connect the engaging members together, if more thanone engaging member is used in the obstruction removal device. Retainingpiece 312 is welded to the hole, and the link can rotate while securedwithin the hole of the engaging member. The engaging members mayindependently rotate.

Engaging member 303 is also connected to the proximal structure 301, asshown in FIGS. 5 and 6. The flared end 308 of the core wire sits pasthole 104 of engaging member 303 and a retaining piece 312 sits over thecore wire 307 to secure the proximal structure 301 to engaging member303, where retaining piece 312 is welded within hole 104. A smaller,gapped coil 311 sits within the distal end of coil 309 and serves tohelp center the core wire 307 within the coil 309.

In one example, the connecting piece 313 is placed within the holestructure, and retaining piece 312 is welded into the hole over theconnecting piece. The flared end 313 can subsequently be laser welded onthe end of the connecting piece. In another example, the retaining piece312 is welded into the hole and the connecting piece is placed within,and the flared end is laser welded. Although laser welding is specified,other similar heat treatment techniques can be utilized as well. Thisprocedure can also be utilized at the end of core wire 307 to produceflared end 308, and to connect proximal-most engaging member 303 to theproximal portion 301 of the device. In one example, this procedure canbe utilized at the end of the coil 316 when connecting the distalportion of the device to distal-most engaging member 306.

Each engaging member has a rotational component; this ability to rotatecan aid in capturing the thrombus and navigating the vessel. This canalso help limit the amount of endothelial denudation that may occur asthe device is being pushed and/or pulled through the vessel, by helpingto limit any excessive forces that build up due to excessive contactfriction between the struts and the vessel wall. The engaging membersmay also be configured to have a more rounded, smoother profile (asillustrated in the figures) which would eliminate any sharp edges on theengaging members which may otherwise promote denudation due to highcontact friction. Furthermore, due to the space between the engagingmembers, less material physically contacts the vessel than other designswhich may utilize, for example, a longer one-piece clot engaging unit.Less material contacting the vessel will also serve to limit endothelialdenudation during the clot removal procedure.

In one example, the proximal portion 301 of the obstruction removaldevice can include means to detach the engaging members from theobstruction removal device. The detachment means can be included on theportion of the proximal portion 301 contacting engaging member 303 (theproximal-most engaging member) and can include electrolytic, mechanical,thermal, or other means known in the art to induce severing and/ordegradation of a linkage.

One or more of the engaging members may actively engage the clot, whileother members can sit either distally beyond, or proximally before, thethrombus—depending on the size of the clot and the number of engagingmembers utilized on the device. Due to the potential variability in theindividual shape and/or profile of each engaging member, as well as thenumber of engaging members used in the obstruction removal devicecompared to the size of the clot, one or more engaging members may sitdistally past the clot and have a denser cell configuration to act as afilter for catching thrombus that may dislodge when capturing the clotutilizing the obstruction removal device.

The engaging member(s) which act as a filter may have a meshconfiguration; said mesh configuration can be throughout the wholeengaging member or be located on one particular side of the engagingmember, in order to maximize the chances of catching loose thrombuswithout the thrombus dislodging. In one example, the engaging member(s)which act as a filter has a denser cell configuration on the more-distalportion of said member in order to catch thrombus dislodged frominteraction of the more proximal engaging members with the clot. Thisarrangement can be useful when the more proximal engaging membersinteract with the clot and portions of the clot macerate. The moredistal engaging members with the filter configuration can catchmacerated thrombus that otherwise might accumulate in the bloodstream.The engaging members which act as a filter may be formed from nitinol,stainless steel, or similar materials.

Alternatively, they may be formed from laser cut polymers.Alternatively, these engaging members acting as filters may have aninverted braid configuration, or other basket-type configurations, orother configurations known within the embolic protection device art. Oneor more of the engaging members may also be composed of a thrombogenicmaterial, or may be coated with a thrombogenic material in order to aidin the clot retrieval procedure, by promoting adhesion between theengaging member and the thrombus. Alternatively, an anti-thrombogenicmaterial can be used, or an anti-thrombogenic coasting can be used inorder to help dissolve a portion of the clot that is in contact with theengaging members. This can be useful with, for instance, retrievaloperations involving a large clot.

FIGS. 7 and 8 illustrate another embodiment of the obstruction removaldevice utilizing one or more engaging members which act as a filter inorder to catch thrombus that may become dislodged during the clotremoval procedure. FIG. 7 illustrates the obstruction removal device,with a proximal portion 401 and distal portion 402. The proximal portionincludes engaging members 303. The distal portion includes engagingmembers 407 and 408. The distal engaging members 407 and 408 have adenser cell configuration to act as a filter to trap dislodged thrombuswhich may shear off during the clot removal procedure, the clot removalprocedure being generally described above. The denser cell configurationis due to an inner and outer structure used to form the engaging member,as illustrated in FIG. 8.

As illustrated in FIG. 8, the two distal engaging members 407 and 408are each composed of an inner structure 409 and outer structure 410,where the inner structure may nest within the outer structure. The innerstructure 409 and outer structure 410 which comprise the distal engagingmembers 407 and 408 may be made from laser cut nitinol, or a similarmaterial. The proximal portion 401 and distal portion 402 are configuredthe same as the embodiment presented in FIGS. 4-5, as are the linkagesbetween each of the engaging members, although this filtering engagingmember structure can be applied to any of the engaging members presentedin any of the presented obstruction removal device embodiments.

The cell pattern may be slightly offset on the inner and outer structurein order to create a denser cell profile when the inner structure isnested within the outer structure. As shown in FIG. 9, the distal part510 of the engaging member 408 has a denser cell profile than theproximal part 511 in order to catch dislocated thrombus which may escapeduring the clot removal procedure. This arrangement can be useful whenthe more proximal engaging members interact with the clot and portionsof the clot macerate. The more distal engaging members with the filterconfiguration can catch macerated thrombus that otherwise mightaccumulate in the bloodstream. Although FIGS. 7 and 8 illustrate twoengaging members having the inner and outer structure to act as afilter, more or fewer engaging members can have this filter structure.

In one embodiment for delivery of the device described in the previousembodiments, an obstruction removal device is sheathed within a deliverydevice, and the delivery device is delivered through a catheter. In oneexample, the delivery device can be a microcatheter. The delivery deviceis delivered to the site of the obstruction and then pulled back.Pulling back the delivery device unsheathes the obstruction removaldevice, such that the engaging members expand upon retraction of thedelivery device.

Alternatively, the obstruction removal device is pushed out of thedelivery device, which subsequently allows the engaging members toexpand. Depending on the number of engaging members on the obstructionremoval device, the size of the clot, and the location of deliveryrelative to the obstruction, some members may sit distally past, and/orproximally before, the obstruction. The obstruction removal device maybe maneuverable via the core wire. Once the obstruction removal deviceengages the obstruction, the delivery device can be withdrawn to a pointjust past the distal end of the catheter, and then the catheter can bewithdrawn. Alternatively, the obstruction removal device can bewithdrawn from the vasculature by withdrawing the delivery device intothe catheter, and subsequently withdrawing the catheter, or withdrawingthe delivery device and/or obstruction removal device through thecatheter. Alternatively, the catheter can be withdrawn wholly to removethe delivery device and obstruction removal device. In another example,the delivery device can be a hypotube.

In an alternative embodiment, the device may be delivered directlythrough the catheter, without being sheathed in a delivery device.

FIGS. 10-12 illustrate an example of a particular method for deployingthe obstruction removal device. In this example, the delivery device 602is delivered through the vasculature 600 to the site of the clot 601.The obstruction removal device 603 is pushed through the delivery deviceto the site of the clot. Although this particular example illustratesthe obstruction removal device deployed in the middle of the clot, thedevice may be deployed within the clot, or in a location proximal ordistal relative to the clot location. Some engaging members may sitdistally past and/or proximally before the clot, depending on the sizeof the clot and the number of engaging members used on the obstructionremoval device. Delivery device 602 is then retracted which allows theengaging members of the obstruction removal device to expand andinteract with portions of the clot. The obstruction removal device 603can be manipulated by the operator from the proximal portion 604 of thedevice. Once the obstruction removal device has secured the clot, thedevice can be withdrawn as described above. Aspiration may also be usedto aid in the clot/obstruction removal procedure. FIGS. 10-12 illustratea particular example for illustrative purposes. Other delivery methodsare contemplated within the scope of the invention, such as pushing theobstruction removal device from the delivery device.

The engaging members may all be the same size, may all be differentsizes, or may have some engaging members sized differently from others.In one example, the diameter range for spherically shaped engagingmembers may be between 1-12 millimeters. In another example, a diameterrange of 3-6 millimeters is used.

The engaging members are formed from a hypotube which is laser-cut intoa particular pattern based on the shape of the struts 101 and cells 102.This hypotube 700 is shown in FIG. 13. The hypotube is heat treated, inone example the hypotube can be heat set at 530-550 degrees Celsius for5 minutes. The hypotube is subsequently quenched in water to cool. Anexpansion plunger 702 is then inserted and used to expand a portion ofthe hypotube (see FIG. 14). The expanded hypotube is then heat-set tothis expanded shape. In one example, it is heat set at 530-550 degreesCelsius for 3 minutes. The expanded hypotube is subsequently quenched inwater. Based on the size of the engaging member, the expansion plungerand subsequent heat treatment step can be used on multiple portions ofthe engaging member, where each section is heat set after expansion. Anexpansion pin 704 is subsequently inserted within the hypotube to helpexpand the walls of the hypotube (see FIG. 15). The expanded hypotube700 is placed in a fixture. The fixture includes two plates 706, 708.Threaded rods connect the plates, and the plates have an externalmounted nut. The nut can be tightened to compress the plates together inorder to further expand the hypotube. Once the appropriate shape is set,the expanded hypotube can be heat treated (in one example, heat treatedat 530-550 degrees Celsius for 5 minutes) and quenched to set the shapeof the engaging member.

The engaging members are subsequently pickled, etched, andelectropolished to set the final shape of the said members. Theobstruction removal device is then assembled together with the one ormore engaging members. Though the engaging members are heat-set andtreated into an expanded shape, they still retain a high degree of shapememory due to factors such as material properties and strut thickness.Thus, the engaging members will adopt an expanded shape when notrestrained (i.e. not sheathed in a delivery device) and will adopt acontracted shape similar to the initial hypotube shape when restrained(i.e. sheathed in a delivery device).

The previous embodiments generally disclosed engaging members in whichall of the struts span the length of the engaging members. Alternativeembodiments can utilize some struts that do not span the length of theengaging members. For instance, those partially-extending struts canextend only along a proximal end of the engaging member and vary inlength relative to each other. These partially-extending struts can helpaugment clot retention capability of the overall obstruction removaldevice.

Please note, for the sake of the embodiments presented in FIGS. 17-18 d,unless otherwise indicated, anything on the left side of the figureswould be considered proximal or in the direction of where vascularaccess was obtained while anything on the right side of the figureswould be considered distal or in the direction of further placementwithin the vasculature.

FIGS. 17, 18 a, 18 b, 18 c, and 18 d illustrate one example embodimentof an obstruction removal device 800 where some struts (e.g., struts801) connect at proximal and distal ends of the engaging members 812 andother struts (e.g., struts 810) only connect at one end of the engagingmembers 812, leaving their other end unconnected/freely floating.

This strut configuration can be seen best in the side view of FIG. 18a ,the proximal end view of FIG. 18b , and the distal end view of FIG. 18c. Specifically, the proximal and distal ends of the engaging members 812have a plurality of smaller struts 805, 807 that generally form aplurality of “flowering” or inclining diamond or loop shapes. Thesediamond or loop shapes are formed of a number of inner struts 805 thatare connected to form a from proximal or distal aperture/hole 800 a/800b and a number of outer struts 807 connected to these inner struts. Forexample, the proximal end of the engaging member 812 includes fivediamond shapes 803 a and the distal end includes three diamond shapes803 b. Put another way, the proximal end of the engaging member 812includes five primary or inner struts 805 radially extending from adistal end of the engaging member. Each of those struts split into a “Y”shape of secondary or outer struts 807, with the distal ends of eachsecondary struts 807 merging together with adjacent secondary struts 807from a different, adjacent primary strut 805.

The five proximal diamond shapes 803 a connect to either a lateral strut801 that spans between the distal diamond shapes 803 b, or a partiallateral strut 810 that does not span the full length to the distaldiamond shapes. As shown in FIG. 18a , some struts can also terminateright where outer struts 807 merge—shown as smaller retained lateralstrut 809. In this way, some struts 801 span between the proximaldiamonds 803 a and distal diamonds 803 b, and some do not.

This configuration can be made in various ways. In one method, thestruts are formed from the hypotube in FIG. 13, which is used to createthe engaging member strut shapes shown, for example, in FIGS. 7-9. Oncethe engaging member is expanded to take on its full shape, some of thestruts are then cut to create the shape shown in FIGS. 17-18. In anothermethod, the hypotube itself which is used to create the engaging membermay have cut-out strut sections so that the finalized engaging membertakes on the shape shown in FIGS. 17-18 d.

In one embodiment, one end of the engaging member 812 can have a largerretained strut-section (i.e., more “diamond” shapes) than the otherend—as shown in FIGS. 17-18 d. In FIGS. 17-18 d, the left side 802 ofthe engaging member 812 (also known as the proximal side of the engagingmember, since the pusher is connected to the left-most engaging memberfor the purposes of the figures) has a larger number of struts 805, 807than the right (or distal) side 804 of the engaging member 812. As bestseen in FIGS. 18a and 18d , this configuration can be made by cutting apreformed lateral strut 801 near the point they would normally mergeinto secondary struts 807. On the other side of the engaging member 812,the strut pairs can be cut at an earlier termination point leaving oneend with a larger retained partial lateral strut 810 and the other endwith a smaller retained lateral strut 809. This configuration furtherenables better proximal gripping of the clot as the device is retractedinto the larger guide or access catheter 817 to evacuate the deviceafter clot retrieval is accomplished.

In other embodiments, the distal end of the engaging member 812 isattached to the larger retained partial lateral strut 810. Thisconfiguration creates a distal net structure to help ensure the ensnaredclot does not travel distally during the clot capture procedure.Alternatively, the individual engaging members can be customized suchthat some engaging members have a larger proximally-retained strutsections, while other engaging members have larger distally-retainedstrut sections. In one example, a clot retrieval device can utilize aproximal-most engaging member with a larger proximally-retained strutsection and a distal-most engaging member with a largerdistally-retained strut section. This configuration would balance thebenefits between augmenting clot retention during retraction through acatheter, while further minimizing the risk of distal clot migrationduring the clot retrieval procedure.

As best shown in FIGS. 18a and 18d , the retained partial lateral struts809, 810 terminate with a marker coil 808. The marker coil 808 isseparately shown in FIG. 19 and has a diameter or thickness that isgreater than the partial lateral struts 809, 810. The marker coil 808 isused to aid in imaging the clot retrieval device and note the locationof the engaging members and whether said engaging members are in anexpanded or collapsed shape. The marker coils 801 can be composed of avariety of radiopaque materials including gold, platinum, tantalum,tungsten, or palladium. Additionally, the marker coil can take on avariety of configurations including a braid, band, or tube. In oneexample, the marker coil 808 is connected onto the struts by using UVglue in the internal diameter of the marker. FIG. 18d showsrounded/ball-like projections 808 a, 808 b on the proximal and distalends of the marker band. In one embodiment, UV glue or laser welding isused in order to create these ball elements which create a securelocking interface between the struts and the marker coil. The markercoil 808 and ball-like projections also provide a larger contact surfaceinterface than the end of the strut sections (as shown in FIG. 18d ) andprovide a larger contacting surface to help engage and retain the clot.Note, the marker coil 808 can alternately be located on the lateralstrut 801 at a location adjacent to termination of either partiallateral strut 809 or 810.

Please note, though the embodiments of FIGS. 17-18 d show individuallinkages between each pair of engaging members (similar to theembodiments of FIGS. 4-8), the engaging members may alternatively sitalong a common structure (similar to the embodiment of FIG. 3).

The following embodiments related to obstruction removal devices inwhich the engaging members strut shapes are configured to help shearthrombus or clot from a vessel wall and can be useful in scenariosinvolving calcified thrombus.

Earlier embodiments of engaging members, such as those shown in FIGS.1-9, utilize struts 101 comprising a lengthy strut section 101 c whichspans the majority of the length of each engaging member. These strutsare aligned in a generally longitudinal orientation in the blood vesselwall thereby mitigating the risk of the struts shearing off the vesselwall surface and damaging the vessel when pushed or pulled. However, insome circumstances it may be desirable to have an obstruction removaldevice that has higher shearing force; for example, in situationsinvolving calcified thrombus or clot attached to the vessel wall inwhich it a large amount of force is necessary to remove or scrape theclot or thrombus from the vessel wall. An engaging member utilizingtwisted lateral strut elements rather than straight strut elements wouldprovide this higher shearing force.

The engaging member 813 shown in FIG. 20 utilizes several lateral strutelements 811 that are not longitudinally aligned between the proximaland distal ends of the member 813, but rather are aligned at an angle(e.g., 1-89 degrees, for instance 45 degrees) relative to aproximal-distal axis of the member 813. This contrasts with the moreaxially-longitudinal or “straight” strut elements 101 c shown in FIGS.1-9. These twisted lateral strut elements 811 create greater surfacecontact between their edges and the vessel wall or clot when pushed orpulled. In this respect, the lateral strut elements 811 can betterscrape the vessel walls to remove hard or calcified clot/thrombus whichmay be attached to the vessel wall. In several embodiments, the engagingmembers are capable of rotation and independent rotation, so as theengaging members rotate, different parts of the strut contact the vesselfurther augmenting the scraping effect against clot/thrombus.

FIG. 21 shows a hypotube shape (shown flattened for illustrativepurposes) with twisted lateral strut elements 811 in the middle whichcorrespond to the twisted strut elements of the engaging member. In oneembodiment, a tube is laser-cut to create the strut shapes of FIG. 21.In one embodiment, a flat sheet is laser-cut to create the strut shapesshown in FIG. 21, then the sheet is rolled around a mandrel and the twoends of the sheet are welded together to create the circular engagingmember shape of FIG. 20. Compared to the hypotube of FIG. 13 whichutilizes substantially straight primary straight sections 101 c (i.e.,those struts that run the majority of the length of the engagingelement), the hypotube of FIG. 21 utilizes angled strut elements 811 tocreate the twisted/angled configuration of FIG. 20. While in FIG. 13,strut elements 101 d and 101 c sit along the same plane, in FIGS. 20-21,strut elements 811 are angled and do not sit along the same plane asmerging strut pairs 801 d.

Other embodiments of an obstruction removal device can utilize multipleengaging members which sandwich the clot from either side to engage andretain the clot. Please note for the following figures, unless indicatedotherwise, anything to the left would be considered distal or in thedirection further downstream within the vasculature while anything tothe right is considered proximal or in the direction where vascularaccess is gained. FIGS. 22-25 show this obstruction removal device 900,which utilizes a distal fixed clot disruptor structure 908 which islocated distal to a clot 910 and a proximal sliding clot catcherstructure 906 which is positioned proximal to the clot 910. The twostructures 906, 908 are connected on a distal portion 902 of a pusher orcore wire 901. The distal clot disruptor 908 is fixed or bonded to thedistal portion 902 of the core wire 901 and the proximal clot catcherstructure 906 can slide along the distal portion 902 of core wire 901,but is prevented (e.g., via a radially enlarged stop portion) fromsliding along the entirety of core wire 901. This sliding can be enabledin a number of ways, for instance in one embodiment, one end 906 a ofproximal clot catcher structure 906 can be connected to a sleeve or bandwhich is positioned over and can slide relative to the core wire'sdistal portion 902.

Various methods can be used to limit the amount that proximal clotcatcher structure 906 can slide. In one embodiment, a proximal and/ordistal stop 906 a can project out from the core wire's distal portion902 in order to limit the amount that the proximal clot catcherstructure 906 can slide. A proximal stop limits the amount the clotcatcher structure 906 slides proximally, a distal stop limits the amountthe clot catcher structure 906 slides distally. In another embodiment,no stop structure is present, however the proximal clot catcherstructure 906 can slide freely solely over core wire's distal portion902. This can be accomplished if the core wire's distal portion 902 issmaller than the remaining proximal portion of core wire 901 such thatthe sliding catcher structure 906 has enough clearance to slide overdistal core wire section 902 but not the rest of core wire 901, sincesaid core wire 901 will be oversized compared to distal core wiresection 902.

The method of use of the obstruction removal device embodiment 900 ofFIG. 22 is described as follows. The physician typically uses a largerguide or access catheter as a sheath for a smaller microcatheter 912which contains the obstruction removal device 900. The physicianadvances the microcatheter 912 in the vessel 904 and through clot 910and then retracts the microcatheter 912 to expose the clot/obstructionretrieval device 900, such that the distal disruptor structure 908 islocated distal to clot 910. The physician then pulls core wire 901,which causes the distal disruptor structure 908 to engage and pushagainst clot 910. Proximal catcher structure 906—which has a degree ofsliding movement but is proximally limited in its movement (as discussedabove)—may move proximally once it contacts clot 910 but will fullyengage the clot once stopped, as shown in FIG. 23. Once the clot 910 isretained by the obstruction removal device 900, the physician canretract core wire/pusher 901 so that the removal device 900 is sheathedinside a larger guide or access catheter 914 and then the whole systemis removed from the patient vasculature.

The proximal clot catch structure 906 and distal clot disruptor 908 cantake on various shapes or designs. One embodiment of an obstructionremoval device 900 is illustrated in FIG. 22 in which the distal clotdisruptor 908 is shaped like the engaging member of FIGS. 1-2; however,other embodiments can utilize a distal clot disruptor 908 shaped likeany of the engaging members shown and described in other engaging memberembodiments presented. In one embodiment, proximal clot catch structure906 is a mesh of braided wires and the proximal end of catch structure906 is closed but slidable over the core wire while the other end 906 bis open to accommodate clot 910. In other embodiments, proximal clotcatch structure 906 is a polymeric structure or even a stent where theproximal end of the stent is secured via a retention means (e.g., amarker band) over the core wire in a slidable manner while the other endof the stent is flared or open to accommodate clot 910. Mesh andpolymeric stents are described in US20130245745 which is herebyincorporated by reference in its entirety and the proximal clotstructure can be one of the stents described therein.

In another embodiment of an obstruction removal device 915, a mesh orpolymeric stent, including those previously incorporated by referenceare used for the distal clot disruptor 908, in which the proximal end ofthe stent is bonded to the core wire 902—as shown in FIG. 24. In anotherembodiment, the proximal clot catch structure 906 takes on theconfiguration of a vessel filter or embolic protection device (EPD).EPD's are often placed downstream of a stent or balloon in a procedureto open a clogged blood vessel, where the EPD is dispatched downstreamprior to the stent or balloon placement in order to catch thrombusdislodged during the procedure. Generally a distal end of the EPD/filterwould be bonded to or over the core wire 902 while the proximal end isan open mouth, since the EPD/filter is placed distal to the treatmentsite. Here, if an EPD/filter is used for the proximal clot catchstructure 906, the proximal rather than distal end of the EPD/filter isbonded in a slidable manner over the core wire since the distal mouth ofthe filter should be open to help entrap the clot. EPD/vessel filtersare described in US2014/0288588, which is hereby incorporated byreference in its entirety. Any of the EPD/vessel filters describedtherein could be used for proximal catch structure 906.

FIG. 25 shows an embodiment of an obstruction removal device 921utilizing multiple members along a core wire. An obstruction removaldevice 921 with multiple members capable of engaging the clot is usefulto remove larger clots, or a clot which is hardened or calcified andwould be otherwise difficult to remove. In this example, there are twoclot catcher structures 916 a, 916 b and two clot disruptor structures918 a, 918 b placed in an alternating manner (e.g. from proximal todistal: a proximal clot catcher 916 a, then a first clot disruptor 918a, then a second clot catcher 916 b, then finally a distal-most secondclot disruptor 918 b). In one example, the proximal clot catcher 916 ais slidable, the first clot disruptor 918 a is fixed or has a limiteddegree of movement, the second clot catcher 916 b is slidable, and thedistal-most second clot disruptor 918 b is fixed.

For embodiments where first clot disruptor 918 a is capable of somelimited degree of motion, there are several ways to allow this. In oneexample, the proximal and distal ends of the first clot disruptor thatsit over the core wire distal section 902 are oversized and the corewire distal section 902 can have built in enlargements so that the firstclot disruptor ends will hit the enlargements to limit movement ineither direction. In another example shown in FIG. 25, the core wiredistal section 902 is segmented rather than continuous. A first leg 902a of the core wire distal section 902 terminates in a ball or enlargedprojection 920 within the first clot disruptor structure 918 a. A secondleg 902 b spans between first clot disruptor 918 a and second clotdisruptor 918 b and terminates in a ball or enlarged protection 920within said second clot disruptor 918 b. The enlargements 920 limit themovement of each clot disruptor since the clot disruptors cannot moveonce the proximal or distal ends of the clot disruptors contact theenlargements. This functions like the obstruction removal device ofFIGS. 4-6, in which engaging members are separated by individual links313 with flared ends which limit translation of the engaging members.Please note, even in the absence of any structures limiting movement ofthe various objects on the core wire, the structures are already limitedin movement since each structure cannot move past the neighboringstructure. For example, the proximal clot catch 916 a can move but theend that slides over the core wire cannot move past the proximal end ofthe first clot disruptor 918 a.

Various versions of the embodiment of FIG. 25 could utilize more clotdisruptors and/or more clot catcher structures, or differentcombinations of clot disruptors and clot catcher structures. Thesegmented core wire system described above, the single core wireenlargement section described above, or combinations of these twosystems can be used to allow limited movement of the various structureson the obstruction removal device.

Many of the obstruction removal device embodiments presented thus farhave utilized engaging members which are capable of independentrotation. Referring to FIG. 26 (which offers another view of the linkageelements originally shown in FIGS. 5-6 connecting the engagingelements), this is possible by utilizing a linkage 1013 between pairs ofengaging members. Linkage 1013 includes two flared ends 1003 (e.g.,enlarged spherical regions) and a retaining piece 1012 (e.g., a cylinderor sleeve) which operate to limit translation of the engaging elementswhile allowing said engaging elements to rotate independently of eachother. Two marker bands 1012 a can also optionally be placed at eitherend of the gap 1015 a between the engaging elements to further aid inimaging. The marker bands 1012 a will also minimize this gap 1015 awhich could potentially be a region where thrombus becomes trapped andlater be sheared away since the small gap results in a small retainingforce. Though the engaging members 1003 are generally capable ofindependent rotation, in scenarios where the engaging members aredeployed in tortuous anatomy or are far oversized compared to the bloodvessel, the engaging members can become stuck in a particularorientation limiting their ability to rotate. This rotation is generallyadvantageous since it allows the engaging elements to self-adjust to thecondition of the vessel which maximizes the chances of clot contact andretention.

FIG. 27 illustrates an embodiment of an obstruction removal device 1050that addresses some of these issues. The device 1050 includes a seriesof engaging members 1052 a-1052 e (five are shown, but more engagingmembers or less engaging members could be used), where each engagingmember is rotationally fixed in a particular orientation. Each engagingmember has substantially the same strut pattern, however each engagingmember is offset a certain number of degrees (i.e. rotated a particularnumber of degrees) from its neighboring engaging member 1052 and eachengaging member is fixed and therefore incapable of independentrotation. As the entire obstruction removal device 1050 is pushed orpulled within a vessel, the fixed, offset arrangement of the engagingmembers 1052 ensure that all interior surfaces of the vessel arecontacted by a strut of the engaging members 1052. In other words, ifall of the engaging members 1052 where aligned in the same rotationalorientation, linear gaps of the vessel's interior may not be contactedby the engaging members 1052. Hence, the rotational offset configurationhelps mitigate this issue, particularly for larger clots that may spanseveral engaging members.

FIG. 28a shows one example involving a rare situation in which eachengaging member is capable of independent rotation but some of theengaging members are stuck in the same or similar rotational orientation(for example, where the engaging members are deployed in a tortuoussection of the vessel or are far oversized compared to the vessel andthereby stuck in one orientation). This figure offers a cross-sectionalview from an end of one of the engaging members. Each end of eachengaging member 1052 has a flowered petal bulb-type shape similar to theone shown in FIG. 1, the strut pairs merge into a lengthier strut whichspans the majority of the engaging member 1052, and this lengthier strutthen diverges into additional strut pairs at the other end of theengaging element and this flowered-type shape is repeated. Here, clot406 is lodged against a particular section of the vessel wall 1068, butthe struts 1064 of two or more neighboring engaging members are stuck ina similar position preventing the clot 1066 from being contacted bystruts 1064. Conversely, in FIG. 28b , the fixed but offset strutorientation offers greater cross-sectional strut coverage around theperiphery of the blood vessel 1068, which enhances the chances that theclot 406 is contacted.

Since the engaging members 10522 a-10522 e are fixed, the rotatablelinking structure of FIG. 26, which includes gap 1015 a, is not needed.In various embodiments, the engaging members can all be welded togetheror formed from one hypotube which is laser cut into the shape shown inFIG. 27. Either configuration will reduce or eliminate the gap betweenthe engaging members which could potentially augment thrombus retentionsince this gap region potentially represents a region where thrombuscould get temporarily stuck but later break free. The engaging memberscan also be placed over an open tubular lumen which spans all of theengaging members. This open tubular lumen can be used as a conduit foradditional devices, including vessel filters placed downstream of theobstruction removal device to catch dislodged thrombus and/or guidewiresused to aid in navigating the placement of the obstruction removaldevice. This design is also considerably simpler than the rotatingengaging element embodiments since the paired linkage configurations areomitted.

In various examples, five engaging members are used and each engagingmember is offset about 36 degrees from the next engaging member. Anotherexample can utilize five engaging members offset about 18 degrees fromthe next engaging member. Other examples can utilize more or lessengaging members with various degrees (e.g., from one degree to 359degrees) of offset, the offset helps ensure a relatively broad crosssection of the vessel will be exposed to at least one strut to aid incontacting the clot, thereby augmenting clot contact and clot retention.In other examples, some engaging members can be offset whereas otherengaging members are not offset. In other examples, different offsetscan be used between different engaging members (e.g. one pair offset by20 degrees, another pair offset by 25 degrees).

Various embodiments of the obstruction removal device, including variousembodiments of the engaging elements comprising the obstruction removaldevice were presented in the specification herein. Please note,different versions of the obstruction removal device can utilize variousengaging element shapes/configurations of different embodiments. Bymeans of example, for the partially spanning strut engaging elementconfiguration of FIG. 18, the engaging elements can utilize the twistedstrut configuration of FIG. 20—alternatively some engaging elements canutilize a twisted strut configuration while others utilize the partiallyspanning strut configuration. Similarly, for the sliding embodiments ofFIGS. 22-25, either the catch structures 906 or disruptor structures 908can utilize partially spanning strut configurations and/or twisted strutconfigurations presented in various other embodiments. Similarly, invarious embodiments (including the partially spanning strutconfiguration of FIG. 18, the twisted strut configuration of FIG. 20, orthe sliding embodiments of FIGS. 22-25) some or all of the engagingmembers can be fixed but offset from other engaging members as shown inFIGS. 27-28 b.

In an alternative embodiment, the device mentioned in the previousembodiments can be used to retrieve foreign objects, in addition toclots or other obstructions. Circumstances may arise where foreignobjects, such as embolic coils normally used to fill an aneurysm, maybreak off or otherwise become detached within the vasculature. Thedevice can be used to retrieve the foreign body utilizing a proceduresimilar to the procedure used during obstruction removal.

FIG. 29 illustrates and embodiment of an engaging member 1070 that,instead of being laser cut, is made from NiTi/Platinum drawn filled tubewires. These wires allow the engaging member 1070 to be fully radiopaqueunder fluoroscopy and therefore allow the physician to better place andcontrol the device during a thrombectomy procedure. The engaging member1070 is illustrated with primary struts 1075, secondary struts 1077 andlateral struts 1071, similar to previous embodiments; through any of theprevious shapes/configurations can be used with these drawn filledtubes. Preferably, each of these struts are formed of individual drawnfilled tube wires that are twisted together, for example at location1079 to connect to adjacent struts. The proximal and distal ends of theengaging member 1070 can be laser welded to marker bands.

FIG. 30 illustrates an engaging member 1079 in which half of the struts805, 807, and 801 are formed via laser cutting a metal sheet/tube, andthe other half is formed of struts 1072, 1075, 1077, and 1078 of drawnfilled tube wires. Preferably, the drawn filled tube wires arepositioned on the distal end of the engaging member 1079 and the lasercut struts are positioned on the proximal end. The laser cut portion canprovide a relatively higher radial expansion force while the drawnfilled tube wires can allow for a greater number of wires to be used andtherefore can increase the filtering capability of the device.Optionally, the drawn filled tube wires can be laser welded to the lasercut portion.

FIG. 31 illustrates another embodiment of an engaging member 1080 havinga plurality of drawn filled tube wires 1075, 1077, 1078 on its proximalhalf in a configuration similar to those previously described, but alsoincludes a distal half 1082 configured as a concave filter. The distalhalf 1082 is preferably formed of a plurality of drawn filled tube wiresthat are braided into the concave shape and welded to the larger drawnfilled tube wires on the proximal half. In this respect, the distal halfcan act as a relatively fine filter and the proximal portion can providethe strength to radially expand the distal portion.

During a thrombectomy procedure, the previously described embodimentsoften much be moved around bends or curves within vessel, which cancause the engaging members to compress, as they seek out the shortestdistance around the curves. This compression of the engaging members cancause the clot to dislodge and therefore be lost. The engaging member1093 shown in FIGS. 32 and 33 address this issue by having a radiallyoffset shape with a relatively straight/flat side 1093 and a relativelycurved side 1098, all formed from struts 1095, 1097, and 1098. As seenin FIG. 33, as the offset engaging members 1093 are pulled around thecurved vessel, their straight/flat side 1093 finds the shortest distancearound the curve while the curved portion 1098 remains fully expanded.

FIG. 34 illustrates another embodiment of a clot retrieval device 1100having a proximal and distal “flowering petal” engaging members 1101that re both connected to a delivery wire 1106. Similar to previouslydescribed embodiments, each engaging member 1101 are composed of aplurality of primary struts 1115 and secondary struts 1117, forming aplurality of connected diamond or loop shapes 1116 (e.g., 5 diamondshapes). The diamond shapes 1116 are included or are opened along adistal direction, forming a distally open cup or concave shape that cancapture a clot 910. Each of the diamond shapes can include a radiopaquemarker 1103 on its distal tip for use in determining their positionduring a procedure. Each engaging member 1101 can be fixed in place tothe wire 1106, slideable on the wires 1106, or a combination of both(e.g., similar to the embodiment of FIG. 22). Preferably, the device1100 is deployed during a procedure so that one engaging member 1101 isproximal to the clot 910 and the other engaging member 1101 is distal tothe clot 910, trapping the clot 910. Alternately, the engaging members1101 can open in the proximal direction or a combination of both (e.g.,the proximal engaging member 1101 opens in the distal direction and thedistal engaging member 1101 opens in the proximal direction).Additionally, more than two engaging members 1101 are also contemplated(e.g., 3, 4, 5, 6, 7, and 8).

Although the invention has been described in terms of particularembodiments and applications, one of ordinary skill in the art, in lightof this teaching, can generate additional embodiments and modificationswithout departing from the spirit of or exceeding the scope of theclaimed invention. Accordingly, it is to be understood that the drawingsand descriptions herein are proffered by way of example to facilitatecomprehension of the invention and should not be construed to limit thescope thereof.

What is claimed is:
 1. An obstruction removal device comprising: aplurality of engaging members; a plurality of linkages; each engagingmember connected to an adjacent engaging member by a linkage, each ofthe plurality of engaging members having a radially expandedconfiguration and a radially compressed configuration; at least oneproximal structure connected to one of the plurality of engagingmembers; each engaging member composed of struts, where some struts spanonly part of a length of the engaging member; wherein the struts thatspan only part of the length of the engaging member terminate in aprojection which is thicker than the struts; wherein the projection is aradiopaque marker, further includes adhesive to bind the struts to theradiopaque marker; and wherein the adhesive forms rounded shapes at bothends of said radiopaque marker.
 2. The obstruction removal device ofclaim 1 wherein the projection is a radiopaque marker coil.
 3. Theobstruction removal device of claim 1 wherein the struts that span onlypart of the length of the engaging member begin at a common region,branch away from each other, and merge at or before the projection. 4.The obstruction removal device of claim 1 wherein the struts definingthe engaging member are slanted relative to the wall of a blood vessel.5. The obstruction removal device of claim 1 wherein at least oneengaging member is fixed and at least one engaging member is sliding. 6.An obstruction removal device comprising: a plurality of engagingmembers; a plurality of linkages; each engaging member connected to anadjacent engaging member by a linkage, each of the plurality of engagingmembers having a radially expanded configuration and a radiallycompressed configuration; at least one proximal structure connected toone of the plurality of engaging members; each engaging member composedof struts, where some struts span only part of a length of the engagingmember; wherein the struts that span only part of the length of theengaging member terminate in a projection which is thicker than thestruts; wherein some of the plurality of engaging members are fixed andradially offset from each other.
 7. An obstruction removal systemcomprising: a plurality of engaging members configured to be transportedthrough a sheath, the plurality of engaging members each adopting acollapsed shape within the sheath and an expanded shape outside of thesheath; a plurality of linkages, each linkage connecting two of theplurality of engaging members; at least one proximal structure connectedto one of the plurality of engaging members; each of the plurality ofengaging members composed of struts, where some struts span only part ofa length of the engaging member; wherein the struts that span only partof the length of the engaging member terminate in a projection which isthicker than the struts; wherein some of the plurality of engagingmembers are fixed and radially offset from each other.
 8. Theobstruction removal device of claim 7 wherein the projection is aradiopaque marker.
 9. The obstruction removal device of claim 7 whereinthe projection is a radiopaque marker coil.
 10. The obstruction removaldevice of claim 7 wherein the struts that span only part of the lengthof the engaging member begin at a common region, branch away from eachother, and merge at or before the projection.
 11. The obstructionremoval device of claim 7 wherein the struts defining the engagingmember are slanted relative to the wall of a blood vessel.
 12. Theobstruction removal system of claim 7 wherein the struts which span onlypart of the length of the engaging member span only a proximal portionof said engaging member.
 13. The obstruction removal system of claim 7wherein the struts which span only part of the length of the engagingmember span only a distal portion of said engaging member.
 14. Theobstruction removal device of claim 7 wherein at least one engagingmember is fixed and at least one engaging member is sliding.